Separation of Linalool from Limonene via Extractive Distillation with 1‑Butyl-3-methylimidazolium Acetate as Entrainer

Orange processing generates a high amount of waste rich in natural compounds that can be used to obtain added-value products or as raw material in biorefineries. Limonene (terpene) and linalool (oxygenated terpene) stand out among those bioproducts due to their organoleptic, antioxidant, and preservative properties. They are widely used in the food, cosmetic, and chemical industries, but their use as generally recognized as safe solvents is also gaining interest. In this work, separation of a mixture of limonene and linalool is proposed by extractive distillation with the ionic liquid 1-butyl-3-methylimidazolium acetate. To that aim, isobaric vapor–liquid equilibrium at 5 kPa was determined for the binary and ternary systems involved, and the data were successfully correlated with the NRTL and UNIQUAC models. The process was simulated, and the recovery of the ionic liquid was tested with a flash unit at very low pressure (0.1 kPa) or a stripping column (5 stages, 101.32 kPa) with air at the maximum operating temperature and a gas–liquid separator (101.32 kPa, 298.15 K). In the second case, an extractive column with an entrainer flow rate of 100 kg/h, number of stages N = 20, and reflux ratio R = 0.5 allows the separation of practically pure limonene and linalool.